Hi,
the same as Steve. I haven't specifically worked with Cobranet, but have been providing ethernet-connectivity for various lighting and audio systems at the largest danish music festival and have family who works with these kinds of systems and basically the concept of having multiple broadcast domains (vlans) which you need connection between is not something the vendors think about.
Experience from this year is that they use the cheapest available layer2 switches for their +100K USD audio equipment, disable STP as this can "break their connection!" as well as igmp snooping - their applications doesn't handle basic igmp join/leaves as it's easier just to ensure that everything is sent to everybody.
So bottom line - I would not expect that you are able to route the traffic, but trunking of the vlans is (as Steve points out).